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SG1844

Current Mode PWMs Isolated Switching Regulators Off-line, 16V UVLO-55°C to125°C

Status: In Production

Features:

  • Optimized For Off-Line Control
  • Low Start-Up Current (<1mA)
  • Automatic Feed Forward Compensation
  • Trimmed Oscillator Discharge Current
  • Pulse-By-Pulse Current Limiting
  • Enhanced Load Response Characteristics -Undervoltage Lockout with 6V Hysteresis
  • Double-Pulse Suppression
  • High-Current Totem-Pole Output (1A Peak)
  • Internally Trimmed Band-gap Reference
  • 500kHz Operation Under-voltage Lockout: SG1844 - 16 volts
  • Low Shoot-Through Current <75mA Over Temperature
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Device Overview

Summary

The SG1844/45 family of control ICs provides all the required features to implement off-line Fixed Frequency, Current-mode switching power supplies with a minimum number of external components. Current-mode architecture demonstrates improved line regulation, improved load regulation, pulse-by pulse current limiting and inherent protection of the power supply output switch.
The Bandgap reference is trimmed to ±1% over temperature. Oscillator discharge current is trimmed to less than ±10%. The SG1844/45 has under-voltage lockout, current-limiting circuitry and start-up current of less than 1mA. The totem-pole output is optimized to drive the gate of a power MOSFET. The output is low in the off state to provide direct interface to an Nchannel device. Both operate up to a maximum duty cycle range of zero to <50% due to an internal toggle flip-flop which blanks the output off every other clock cycle. The SG1844/45 is specified for operation over the full military ambient temperature range of -55°C to 125°C. The SG3844/45 is designed for the commercial range of 0°C to 70°C.

Additional Features
    • Optimized For Off-Line Control
    • Low Start-Up Current (<1mA)
    • Automatic Feed Forward Compensation
    • Trimmed Oscillator Discharge Current
    • Pulse-By-Pulse Current Limiting
    • Enhanced Load Response Characteristics -Undervoltage Lockout with 6V Hysteresis
    • Double-Pulse Suppression
    • High-Current Totem-Pole Output (1A Peak)
    • Internally Trimmed Band-gap Reference
    • 500kHz Operation Under-voltage Lockout: SG1844 - 16 volts
    • Low Shoot-Through Current <75mA Over Temperature
Parametrics
Name
Value
Regulator Type
HI Rel Switching Regulators
Configuration
Current Mode PWMs
Supported Topology
Power MOSFET Driver
Supported Output
1
Minimum Input Voltage (V)
30
Maximum Input Voltage (V)
30
Output Current (mA) Max
1000
Maximum Frequency (kHz)
500
Operating Temperature Range (°C)
-55 to 125
Vref (V)
5
Duty Cycle Max (%)
48
UVLO
Yes
Current Limit
Yes

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